Add utc mode

[timrwood]

See comments starting here.

#147 (comment)

[timrwood]

Perhaps there can be a switch between utc and local time. Something like this maybe.

moment().utc().format('YYYY-MM-DD') // format in utc time
moment().format('YYYY-MM-DD') // format in local time

The utc flag would stay with the object, and then it could be removed as well.

var a = moment().utc();
a.format() // format in utc time
a.local() 
a.format() // format in local time

Then we could also add a parsing function to the root object (not the prototype) to create the moment in utc time.

moment.utc('10-10-2012', 'MM-DD-YYY'); // same as below
moment('10-10-2012', 'MM-DD-YYY').utc(); // same as above

[deepwell]

I'm happy with that.

[icambron]

+1

[timrwood]

This is done